Let a compact topological group $G$ with invariant measure $\mu,$ acts on a simply connected compact topological space $X$ and $\rho$ is a $n$-dimensional unitary representation of $G$. Let $f:X\to M_{n}(\mathbb{C})$ be a continuous function. Under what of the following two conditions we can say:
There exist $x_{0}\in X$ such that the following integral is non invertible:
$$ \int_{G} \rho(g)f(g.x_{0})d\mu $$
Condition 1: $G$ is abelian and $\rho$ is a non trivial representation.
Condition 2: $\rho$ is an irreducible representation.
In particular is the following statement true:
Assume that $\phi$ is a order $n$ homeomorphism on $S^{4}$ and $\lambda \neq 1$ is a quaternion with $\lambda^{n}=1$.Assume that $f:S^{4}\to \mathbb{R}^{4} \simeq \mathbb{H}$ is a continuous function. then there is a point $x_{0}\in S^{4}$ such that $\sum_{i=0}^{n-1} \lambda^{i}f(\phi^{i}(x_{0}))=0$.
Note that the particular case $\lambda=-1$ and $\phi=$ The antipodal map is the classical Borsuk Ulam theorem.
The motivation for the last part of the question is that the above statment is true if we replace $S^{4}$ and $\mathbb{R}^{4}$ by $S^{2}$ and $\mathbb{R}^{2}\simeq \mathbb{C}$, respectively and choose $\lambda \in \mathbb{C}$.